Two Aussies Hurt In London Rampage That Left One Woman Dead

An American woman has been killed and five other people injured, including two Australians, by a man with suspected mental health issues who went on a rampage with a knife in central London.

Armed police were called late on Wednesday evening after a 19-year-old Norwegian man of Somali origin began attacking people in London's Russell Square, a park near the site of a 2005 suicide bombing. Police said there was no evidence the attack was terrorism related.

The victim was identified as Darlene Horton, a woman in her 60s who was the wife of a US psychology professor. She was treated at the scene but pronounced dead a short time later.

A British man who was stabbed in the stomach remains in hospital in serious but stable condition, police said.

Australia's Department of Foreign Affairs and Trade confirmed that two Australians, a man and a woman, received non-life threatening injuries in the attack.

The man, stabbed in the chest, and the woman, stabbed in the back, have both been released from hospital.

An American man and an Israeli woman also suffered stab wounds but have also been released from hospital.

"All of the work we have done so far increasingly points to this tragic incident as having been triggered by mental health issues," London Metropolitan Police Assistant Commissioner Mark Rowley said.

"We believe this was a spontaneous attack and that the victims were selected at random," said Britain's senior anti-terrorism officer.

"So far, we have found no evidence of radicalisation that would suggest that the man in our custody is in any way motivated by terrorism."

Police, who arrived within six minutes of being called, used a Taser to subdue the suspect and he was later formally arrested on suspicion of murder.

London's Sadiq Khan, the first Muslim mayor of a major Western capital, called for vigilance and urged Londoners to report anything suspicious to the police.

"The safety of all Londoners is my number one priority and my heart goes out to the victims of the incident in Russell Square and their loved ones," he said.

The woman who was killed was identified as Horton by Florida Governor Rick Scott. Florida State University said in a statement she was married to an eminent professor of psychology who had been teaching in its London Study Program.

"There are no words to express our heartache over this terrible tragedy," FSU President John Thrasher said.

Just hours before the attack, London's police chief said that he would deploy an additional 600 armed officers across the capital to protect against attacks.

London counter-terrorism police chiefs have previously warned that Islamic State was seeking to radicalise vulnerable people with mental health issues to carry out attacks.

Islamist militants hit London with coordinated suicide bombings on July 7, 2005, killing 52 people. One of the bombs detonated on a bus close to Russell Square.

Since then, dozens of plots have been foiled and there have been smaller-scale attacks, such as the beheading of an off-duty soldier by militant Islamists in a London street in May 2013.